Recently, virtualization technology whereby virtual machines (VMs) run on a physical server has been used. For example, there is an increasing number of data centers in environments in which virtual machines run on a physical server through the use of virtualization programs. The virtualization programs have capabilities of moving virtual machines running on a physical server onto a physical server of another data center. Such movement of a virtual machine is referred to as “migration”.
The following techniques using the capabilities of migration have been proposed. For example, there is a technique in which, once one of a plurality of data centers coupled so as to be capable of mutually transmitting and receiving data receives information of a disaster, the system is moved to a data center that is not affected by the disaster. Examples of the related art documents include Japanese Laid-open Patent Publication No. 2010-237926, Japanese Laid-open Patent Publication No. 2011-209811, and International Publication Pamphlet No. WO 2010/050249.